Lifting device
BACKGROUND OF THE INVENTION 
     This application is a continuation-in-part of prior co-pending application Ser. No. 126,593 filed Nov. 30, 1987, now U.S. Pat. No. 4,911,600; which is a continuation of prior application Ser. No. 862,015, filed May 12, 1986, now U.S. Pat. No. 4,741,068, which was a continuation of prior application Ser. No. 572,389, filed Jan. 20, 1984, now abandoned. 
     The present invention relates to lifting devices for refuse collection vehicles and the like. 
     Before the present invention, lifting devices have been proposed for emptying containers into the cavity of a vehicle, such as refuse trucks. An initial problem with prior devices is that they are large and cumbersome. Also, the prior lifters have prevented access to the vehicle for pivot dumping large rear loading containers. One prior device folds to a side of the vehicle to permit access to the vehicle, but the device obstructs traffic in this position. 
     SUMMARY OF THE INVENTION 
     A principal feature of the present invention is the provision of an improved lifter emptying container into a cavity of a vehicle which does not interfere with access for pivot dumping large rear loading containers. 
     In a preferred embodiment, the lifter of the present invention comprises a first plate pivotally mounted to the vehicle and a second plate extending at an angle from the first plate. The lifter has a third plate mounted on the second plate, with the third plate having a pair of spaced hooks. The lifter has means for driving the plates and hooks between a first lower, retracted position to a series of second upper position. 
     A feature of the present invention is that in the first position the lifter is located beneath the vehicle. 
     Thus, a feature of the present invention is that when the lifter is at the first position access is permitted to the vehicle in order to dump a large rear loading container into the vehicle. 
     Another feature of the invention is that the hooks grasp bars on the container as the lifter moves between the first and second positions. 
     Yet another feature of the invention is that the lifter places the container above the cavity at the second position in order to empty the container into the vehicle cavity. 
     A further feature of the invention is that one of the hooks clamp on the container bar to prevent the container from falling into the cavity while it is being emptied. 
     Still another feature of the invention is that the hooks are adjustable in height on the lifter. 
     Thus, a further feature of the invention is that the lifter may be adjusted to accommodate changes in the truck as refuse is dumped into the vehicle or differences in height when the vehicle is located on a hill. 
     Further features will become more fully apparent in the following description of the embodiments of this invention and from the appended claims. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a fragmentary perspective view illustrating a lifter of the present invention in a first lower position; 
     FIG. 2 is a fragmentary perspective view of the lifter of FIG. 1; 
     FIG. 3 is a perspective view of a container which is emptied into a vehicle by the lifter of the present invention; 
     FIG. 4 is a fragmentary perspective view of the lifter in a second upper position; 
     FIG. 5 is a fragmentary sectional view taken substantially as indicated along the line 5--5 of FIG. 4; 
     FIGS. 6-8 are fragmentary perspective views illustrating the lifter in operation to empty the container into the vehicles; 
     FIGS. 9 and 10 are diagrammatic views illustrating operation of the lifter of the present invention; 
     FIG. 11 is a view from the back of a truck illustrating an alternative embodiment of the present invention in an intermediate position between the first lower position and the second upper position; 
     FIG. 12 is a fragmentary perspective view illustrating an alternative embodiment of the present invention in an intermediate position, and, in phantom lines, in the first lower position; 
     FIG. 13 is a fragmentary perspective view illustrating an alternative embodiment of the present invention in the second upper position; and 
     FIG. 14 is a fragmentary sectional view of a self-tensioning rod taken substantially as indicated along the line 14--14 of FIG. 13. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, there is shown a lifter 20 of the present invention which is mounted by bolts 21 on the rear of a vehicle V such as a refuse truck. Although the lifter 20 is shown mounted on the right rear side of the vehicle V, it will be understood that another lifter of the same type may be mounted on the left side of the vehicle V. The vehicle V has a hopper container sill S defining a lower portion of a rearwardly facing opening to the cavity C&#39; to receive and retain refuse. The sill S has a lower portion L slanting upwardly and rearwardly to a leading sill edge E over which the refuse is dumped. As shown in FIG. 1, the lifter 20 is located at a first, or lower, position beneath the sill S of the vehicle V, with the lifter 20 being mounted by the bolts 21 adjacent but beneath the edge E of the sill S to permit horizontal access to the edge E from the edge E to the ground. The lifter 20 of the present invention is utilized to empty a first type of containers C of FIG. 3 into the cavity C&#39; of the vehicle V of a type which are too short to matingly engage the sill and thus must be lifted above the sill. With reference to FIG. 1, with the lifter 20 in its lower, or retracted position the lifter 20 is located sufficiently beneath the sill S, such that access at a level vertically beneath the edge E to the ground is permitted to the rear sill S at the of the vehicle in order to empty large, rear-loading containers C&#34; of the type which are tall enough to be unloaded by tilting without lifting, as shown in FIG. 1, in a tilted position. Before and after dumping of the container C&#34; extends substantially vertically from the sill edge E toward the ground. The container C&#34; has an elongated trunnion bar T at an uppermost portion of the container C&#34; which is located adjacent to the sill edge when the container C&#34; is dumped, as shown in FIG. 1. Thus, in accordance with the present invention, the lifter 20 lifts and tilts small containers without interfering with the emptying of both small and large containers into the vehicle V. 
     With reference to FIG. 3, the container C with which the lifter 20 operates has a lower front bar B and an upper front bar B&#39;. The container C has a chamber C&#34; with an open top into which refuse is dumped by the user for storage until the container C is emptied into the vehicle V of FIG. 1. 
     With reference to FIGS. 1, 2, 4, and 5, the lifter 20 has a first plate 22 having an inner end pivotally connected at 24 to the rear of the vehicle V adjacent the cavity C&#39;. The lifter 20 has a second plate 26 extending therethrough for a purpose which will be described below. Also, the second plate 26 has a pair of spaced rods 30 at opposed sides of the second plate 26 and extending along the second plate 26. 
     The lifter 20 has a third plate 32 having a pair of flanges 34 at opposed sides of the third plate 32 and partially extending around the rods 30 of the second plate 26, such that the third plate 32 is slidably mounted on the second plate 26. The third plate 32 has a first set of openings 36 aligned along the third plate 32, and a second set of openings 38 aligned along the length of the third plate 32, such that the openings 36 and 38 register with the apertures 28 of the second plate 26. The third plate 32 has an upper outwardly directed hook or hook member 40 adjacent an inner end of the third plate 32. The third plate 32 also has an outwardly directed flange 42 adjacent an outer end of the third plate 32. 
     The third plate 32 has an inner tunnel 44 adjacent an outer end of the third plate 32. The third plate 32 has hook means comprising a tongue 46 slidably received in the tunnel 44, and a hook or hook member 48 extending from an outer end of the tongue 46 and being directed toward the flange 42. The lifter 20 has a pair of elongated opposed flanges 50 connected to an inner end of the tongue 46, with the flanges 50 having a plurality of apertures 52 spaced along their length. 
     The lifter 20 has a hydraulic cylinder 54 having one end pivotally connected at 56 beneath the vehicle. The cylinder 54 has a piston 58 which may move in and out of the cylinder 54. The piston 58 of the cylinder 54 is driven by a pump 60 through conduits 62, with the pump 60 being driven by a motor 61 which is powered by the electrical system of the vehicle V. 
     The lifter 20 has a pair of link arms 64 each having an inner end pivotally connected at 66 to the vehicle V, and an outer end pivotally connected at 68 to an outer end 70 of the piston 58. The lifter 20 has an arcuate arm 72 having one end 74 pivotally connected to the outer end 70 of the piston 58 and outer ends of the link arms 64 at connection 68, and the other end 76 pivotally connected at 78 to an inner end of the first plate 22. 
     The lifter 20 has a pair of rods 80 having one end pivotally connected at 82 to a central portion of the arcuate arm 72 intermediate the pivotal connections 68 and 78. The other ends of the rods 80 have pins 84 which are pivotally received in selected apertures 52 of the flanges 50. 
     In operation, the lifter 20 is initially located in a first lower position beneath the vehicle V, as shown in FIG. 1. In this configuration, the hook 48 is spaced from the flange 42. Prior to use of the lifter 20, the container C of FIG. 3 is moved to a position behind the lifter 20. With reference to FIG. 6, as the cylinder 54 is operated by the pump 60 and motor 61 to drive the piston 58 out of the cylinder 54, the lifter 20 moves from beneath the truck and the hook 40 initially catches the upper bar B&#39; of the container C. With reference to FIG. 7, as the piston 58 is driven further from the cylinder 54, the lower bar B of the container C is received between the hook 48 and the flange 42. Next, as the cylinder 54 further drives the lifter 20 in an upward direction, the hook 48 moves toward the flange 42 in order to clamp the lower bar B of container C between the hook 48 and flange 42 and prevent the container C from falling into the cavity C&#39; of the vehicle V. Finally, with reference to FIG. 8, the lifter 20 is driven to a second upper position with the container C located above the cavity C&#39; of the vehicle V in an upside down orientation in order to empty the container C into the cavity C&#39; of the vehicle V. After the container C has been emptied into the vehicle V, the lifter 20 is driven from the second upper position to the first lower position while the hook 48 moves away from the flange 42 in order to release the lower bar B of the container C. In this manner, the lifter 20 of the present invention may be readily and simply used in order to empty the container C into the cavity C&#39; of the vehicle V. 
     The manner in which the hook 48 is moved toward and away from the flange 42 during movement of the lifter 20 will be discussed in connection with FIGS. 9 and 10 where the lifter 20 is shown in solid lines in a lower position and in dotted lines in an upper position. As shown, the pivotal connections 78, 82, and 84 are located on nearly a straight line at the lower position of the lifter 20 and define a distance L between the connections 78 and 84. In the upper position of the lifter 20, the connections 78, 82, and 84 form a triangle to define the distance L&#39;. Therefore, it will be apparent that the distance L&#39; between the connections 78 and 84 is less in the upper position of the lifter 20 than the distance L in the lower position of the lifter 20. Accordingly, the rods 80 pull on the tongue 46 as the distance between connections 78 and 84 lessens while the lifter 20 rises, and the tongue 46 moves the hook 48 over the bar B as the lifter 20 rises and the distance L shortens. In this manner, the hook 48 is clamped on the bar B as the lifter 20 moves toward its upper position. In a preferred form, the hook 48 clamps on the bar B when the lifter 20 is approximately in a horizontal position. In reverse, as the lifter 20 lowers from its upper position the distance L&#39; increases and the rods 80 move the tongue 46 and hook 48 toward an outer position in order to release the bar B. In this matter, the lifter 20 of the present invention clamps the bar B of the container C as the lifter rises to its second upper position in order to prevent the container from falling into the cavity , C&#39; of the vehicle as the container C is emptied. 
     As refuse is placed in the cavity C&#39; of the vehicle V, the vehicle V settles and the height of the hooks 48 and 40 may change with respect to the bars of the container C. Also, when the vehicle is placed on a hill, the height of the hooks 48 and 40 may change relative to the bars of the container C. In accordance with the present invention, the height of the hooks 48 and 40 may change relative to the bars of the container C. In accordance with the present invention, the height of the hooks 48 and 40 may be adjusted relative to the bars B and B&#39; of the container C to accommodate these changes. The openings 36 and 38 of the third plate 32 may be selectively positioned in register with the apertures 28 of the second plate 26 as the third plate 32 is slid relative to the second plate 26. Once the selected openings 36 and 38 are in register with the apertures 28, a pair of pins 86 are placed through the openings 36 and 38 and the apertures 28 in order to retain the third plate 32 in place relative to the second plate 26. Prior to adjustment of the third plate 32, the pins 84 of the rods 80 are removed from the apertures 52 of the flanges 50, and the pins 84 are then inserted into different apertures 52 of the flanges 50 depending upon the location of the third plate 32. Of course, the position of the hooks 48 and 40 are fixed with respect to the third plate 32, and thus the height of the hooks 48 and 40 are adjusted relative to the container C through adjustment of the position of the third plate 32 in the manner described. 
     Thus, in accordance with the present invention, the lifter 20 may be positioned beneath the vehicle V to permit access to the vehicle V and empty large rear loading containers into the vehicle V. Also, the lifter 20 grasps a container C during movement to a second upper position in order to empty the container C into the vehicle V. In accordance with the invention, the lifter 20 has a hook 48 which clamps on a bar B of the container C curing upward movement of the lifter 20, in order to prevent the container C from falling into the cavity C&#39; of the vehicle V as the container C is being emptied, and the hook 48 automatically releases the bar B of the container C as the lifter 20 moves from its upper to lower position. Also, the height of hooks 48 and 40 of the lifter 20 may be adjusted relative to the bars B and B&#39; of the container C such that the hooks 48 and 40 appropriately grasp the bars B and B&#39; on the container C curing operation of the lifter 20. 
     FIGS. 11-14 depict an alternative embodiment of the present invention which utilizes a pivotally mounted hook 88 for capturing the lower bar B of the container C. To accommodate dimensional variations which may occur in construction of the lifter or which may arise due to wear, a variable length means, such as variable length connector 90, is provided for pivoting the hook 88 between a capture or latch position (as shown in FIG. 13) and an open or release position (as shown in FIG. 12). 
     Referring to FIG. 12, the lifter 20 of this embodiment has many of the same features as were described in connection with the first-recited embodiment. The lifter has a flat plate portion 92 which is pivotally connected at 94 to the rear of vehicle V generally adjacent and below the sill S of cavity C&#39;. An additional or second flat plate portion 96 is attached, as by welding, to the outer or distal end of the first plate 92, and extends at an angle of approximately 90° or slightly greater to the first plate. To provide reinforcement, two generally triangularly shaped plates 98 are welded to the underside of the first and second plates. 
     As with the earlier-described embodiment, for pivoting the lifter between a retracted position (in dashed lines in FIG. 11) and an extended position (FIG. 13), the lifter includes a hydraulic piston/cylinder combination 100 having one end pivotally connected at 102 beneath the vehicle. As with the prior embodiment, the hydraulic cylinder is preferably driven by a pump through conduits in a manner earlier described and well-known to those skilled in the field. 
     The hydraulic piston/cylinder combination 100 moves the lifter through a system of linkages best shown in FIGS. 12 and 13. A first link 104 is pivotally attached to the vehicle V at one end, and to a second link 106 at the other end. The second link 106 is also pivotally attached to a bracket 108 mounted on the underside of plate 92. The first link 104 in the illustrated embodiment is angled to conform to the depicted underside of the vehicle V when the lifter is in the retracted position. The second link is also angled or arcuate to provide means for pivoting the hook 88 between the capture and release positions. As shown in FIG. 12, connector 90 is pivotally attached at one end 112 to the second link 106. The other end of the connector is pivotally attached at 114 to the hook 88. Preferably, the pivotal attachment point 112 of the connector 90 to the second link is at a location spaced from an imaginary line connecting the end pivot points of the second link. With this attachment point, movement of the lifter between retracted and extended positions results in a pulling or pushing force on the connector (as described earlier with respect to FIG. 10) and movement of the hook between an open or release position and a closed or capture position. 
     For engaging and lifting a container C, the lifter preferably includes a fixed, upwardly extending hook 116 for engaging under the upper bar B&#39; of the container so as to lift the container as the lifter is moved from the retracted to the extended position. To prevent the container C from disengaging from the lifter when it is inverted for discharge of the contents (see FIG. 13), a lower stop, such as an angle-iron bracket 118, is provided on plate 96, against which the lower bar B of the container C engages when the container is inverted. 
     To capture the lower bar B against the stop 118 and prevent accidental disengagement, the lifter includes the pivotally mounted hook 88. The hook preferably is curved at one end for capturing the bar B and is pivotally attached to the connector 90 at the other end. The hook 88 is preferably pivotally mounted (at a point intermediate the ends) on the backside of plate 96 for pivotal movement of the curved end portion through an aperture in the plate between a retracted position, such as shown in FIG. 12, and a capture position, such as shown in FIG. 13. As seen in FIG. 12, the hook, when in the open or release position, is pivoted upwardly and away from the stop 118. In the capture position, the hook is pivoted downwardly toward the stop, and may rest against the stop, with the curved end portion of the hook overlying and generally capturing the bar B against accidental dislodgement of the container. 
     As noted earlier, the hook 88 is pivoted between the capture and release positions by variable length connector 90. To accommodate variations in dimensions which may occur during construction or during use, the connector 90 is preferably of variable length or extensible to avoid imposing undue stress on the hook 88. An example of how undue stress may arise, as will be seen in FIG. 13, when in the capture position, the hook may engage against the stop 118. If the connector 90 were of rigid construction, and variations during construction of the lifter resulted in the hook engaging the stop prior to the lifter reaching the end of its upward travel, further upward movement of the lifter would result in very large forces being applied to the connector and the hook resulting in possible bending or fracture of the hook or possible fracture of one or more of the component parts of the hook or the connector. 
     To avoid placing too great a stress on the hook, the connector 90 is preferably extensible or of variable length. Although various means may be used for providing variability in length, in the preferred embodiment, connector 90 is spring-loaded to allow it to increase in length and is constructed in a manner depicted in detail in FIG. 14. As shown there, the connector 90 comprises a cylindrical housing, generally at 120, and an axially movable rod 122. The housing 120 has an attachment eye 124 welded at one end, and a cap or cover 126 welded at the other end, with an aperture therein through which the rod 122 may move. The rod is preferably spring-loaded by a spring 128 located between the cover 126 and a sleeve 130 which is welded to the interior end of rod 122. The spring is preferably pre-compressed to exert a force on the rod of approximately 30 lbs. The spring constant is preferably about 30 lbs./inch. 
     To reduce friction between the rod 122 and the housing 120, the interior of the housing 120 may be packed with lubricating grease or its equivalent as is well-known in the art. To allow periodic injection of grease into the housing 120, a grease fitting 132, as is well-known in the art, may be provided in housing 120. An annular grease seal 134 is provided on the aperture cover 126, serving to retain the grease in the housing 120 while permitting the rod 122 to slide through the grease seal 134 relative to the housing 120. In the preferred embodiment, the annular grease seal is made of an elastomeric or resilient material such as rubber. Any other suitable seal material compatible with grease may, however, be substituted without departing from the spirit of the invention. 
     The length of the entire connector 90 is such that when the lifter 20 is pivoted from the retracted position to an intermediate position, such as shown in FIG. 12, where it engages and begins to lift a container C, the rod exerts a pushing force on the hook 88, moving it upwardly and away from the stop to allow rod B to engage or nest against the stop 118. Upon further rotation of the lifter upwardly to a tilting position, the second link 108 exerts a pulling force on the connector 90, causing the hook 88 to pivot downwardly over the stop 118 and bar B, and capturing the bar in a position against the stop from which it cannot inadvertently dislodge, as shown in FIG. 13. 
     In the event variations in dimensions arise during construction of the dumper or from use which result in the hook engaging against the stop prior to the lifter reaching its end of upward travel, further rotation of the dumper upwardly will result in the connecting rod 90 being extended, via compression of the spring, thereby holding the hook tightly in the capture position but without inducing unnecessary stress which would result in bending or fracture of the hook or other components. 
     In operation, this embodiment of the lifter 20 is initially located in a first lower position beneath the vehicle V, as best seen in FIG. 12, in the phantom lines. Prior to use of the lifter 20, the container C of FIG. 3 is moved to a position behind the lifter 20. With reference to FIG. 12, as the cylinder 100 is operated by the pump 60 and motor 61 to drive the piston out of the cylinder, the lifter 20 moves from beneath the truck and the hook 116 initially catches the upper bar B&#39; of the container C. Next, as the cylinder 100 drives the lifter in an upward direction, the motion of hook 88 rotates downwardly over stop 118 and over the lower bar B of the container C without hitting container C. The latching of hook 88 prevents the container C from falling from the lifter during continued rotation of the lifter to an inverted position. 
     Finally, with reference to FIG. 13, the lifter 20 is driven to a second position with the container C located above the cavity C&#39; of the vehicle V in an upside-down orientation in order to empty the container C into the cavity C&#39; of the vehicle V. After the container C has been emptied into the vehicle V, the lifter 20 is driven from the second upper position to the first lower position while the hook 88 rotates upwardly over the lower bar B of the container C. In this manner, the lifter 20 of the alternative embodiment of the present invention may be readily and simply used in order to empty the container C into the cavity C&#39; of the vehicle V. 
     The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.